Pressure sensor

1. Technical Field

The present invention relates to a pressure sensor employed in a stability control apparatus for a vehicle, and more particularly, to a pressure sensor, which makes it possible to be in stable contact with an electronic control unit under a condition where an excessive vibration is generated.

2. Description of the Related Art

In general, a vehicle is provided with a brake system for reducing speed or braking. The brake system comprises a pedal for transmitting driver\'s operating force, a booster and a master cylinder connected to the pedal to generate brake oil pressure, and a wheel brakes for braking wheels of the vehicle according to the brake oil pressure inputted from the booster and the master cylinder.

In the brake system, when the driver steps on the brake pedal to generate the braking force, if the braking force is larger than a road friction force or the friction force generated on the wheel brake by the braking force is larger than the braking force generated on a tire or road surface, a slip phenomenon where the tire skids on the road surface is generated.

In the meantime, in a state where the brake operates as described above, a steering system becomes locked, and thus, the driver cannot steer the vehicle in his or her desired direction.

Accordingly, an anti-lock brake system (ABS) which electronically controls brake pedal force has been developed such that a driver can steer a vehicle in his or her desired direction when the slip phenomenon is generated.

The anti-lock brake system comprises a hydraulic unit to which a plurality of solenoid valves, low-pressure accumulators and high-pressure accumulators for adjusting brake oil pressure to be transmitted to the wheel brake and an electronic control unit (ECU) for controlling components that electronically operate.

The hydraulic unit is also provided with a pressure sensor for sensing brake operating pressure generated in the master cylinder in proportion to the brake pedal force generated by a driver and transmitting an electrical signal on the sensed brake operating pressure to the electronic control unit. The electronic control unit controls the operation of the brake in response to the electrical signal transmitted from the pressure sensor.

FIG. 1 is an exploded perspective view of a pressure sensor 10 according to a prior art. Referring to FIG. 1, the pressure sensor 10 is mounted in a hole formed at a leading end of a master cylinder and electrically connected to a circuit board of an electronic control unit through additional connector and cable.

The pressure sensor 10 comprises pin members 24, which is in contact with the circuit board of the electronic control unit, and a lower guide 26, which guides movement of the pin members 24 and to which a contact board 22 is coupled. In addition, a spring 25 is coupled to each of the pin members 24 to elastically support the pin member 24.

Furthermore, an upper guide 18 is coupled to an upper portion of the contact board 22, and an electric component module 16 having a pressure sensing unit and a control unit provided therein is coupled to an upper portion of the upper guide 18. In the meantime, springs 20 electrically connecting the contact board 22 and the electric component module 16 are installed to the upper guide 18.

Also, a sensor module 14 in which various kinds of sensors are mounted is installed to an upper portion of the electric component module 16.

The various kinds of components of the pressure sensor 10 are integrally configured by a housing 12. In the meantime, O-rings 12a and 12b are installed at upper and lower portions of the housing 12.

In a case where the braking force is generated by the driver\'s brake pedal force, an electrical signal is generated in the pressure sensor 10 by a small vibration. Then, the pressure sensor 10 is electrically connected to the circuit board by the pin members 24 which are elastically urged by the springs 25, whereby the electrical signal generated in the pressure sensor 10 is transmitted to the electronic control unit.

However, the pressure sensor 10 according to the prior art has a problem in that if large vibration is generated, the springs 20 and 24 may be compressed and thus the pin member 24 may be separated from the circuit board of the electronic control unit. Also, in the conventional pressure sensor 10, the pin members 24 are not accurately connected to terminals of the circuit board, whereby signal transmission or electrical connection becomes unstable due to a contact error caused by the inaccurate connection. Furthermore, in the conventional pressure sensor 10, since the pin members 24, which are in contact with the circuit board, are made of a rigid material, when shock is applied, the pin members 24 are inertially moved by vibration and the like, so that a contact error can be easily generated. There is a problem in that a connecting terminal of the circuit board is damaged by shock or friction generated between the pin members 24 and the circuit board. Also, there is a problem in that when lateral vibration is generated, the conventional pressure sensor 10 cannot absorb this lateral vibration appropriately. As described above, if the contact error between the conventional pressure sensor 10 and the electronic control unit is generated, this contact error acts as the factor affecting the steering and braking performances of a vehicle. Accordingly, development for a pressure sensor that can be connected to a circuit board of an electronic control unit through a new method is desired.

The present invention is conceived to solve the aforementioned problems in the prior art. According to one embodiment, a pressure sensor is provided, which can be in stable connect with a circuit board of an electronic control unit, has a simple coupling structure without soldering, and can be securely mounted to prevent signal transmission or electrical connection caused by vibration and the like from being interrupted.

According to one embodiment, a pressure sensor has an improved inner structure to allow the pressure sensor to be stably connected to a circuit board, can prevent a coupling error from occurring to easily perform an assembling process, and can absorb lateral vibration.

According to one aspect, there is provided a pressure sensor installed to a hydraulic unit and being in contact with a circuit board of an electronic control unit to sense brake oil pressure. The pressure sensor comprises a connecting terminal formed on the circuit board of the electronic control board and comprising a press-fit terminal; a press-fit being in slidable and movable contact with the press-fit terminal; and a spring connecting the press-fit and the press-fit terminal.

Further, the press-fit terminal preferably comprises a central portion having a lower end coupled to the connecting terminal of the circuit board and electrically connected thereto, and a pair of extension portions extending upward from both sides of the central portion, the press-fit terminal having elasticity for allowing the ends of the extension portions to be in elastic contact with the press-fit. Furthermore, the press-fit terminal may comprise a guide portion formed on the end of the extension portion to be inclined outwardly for allowing the press-fit to be easily inserted thereinto.

In addition, according to another aspect, there is provided a pressure sensor installed to a hydraulic unit and being in contact with a circuit board of an electronic control unit to sense brake oil pressure. The pressure sensor comprises a contact terminal being in contact with the circuit board of the electronic control unit, wherein the contact terminal consists of a first coil spring portion being in contact with the circuit board of the electronic control unit and a second coil spring portion extending from the first coil spring portion to connect to the pressure sensor, the first coil spring portion having a winding density larger than that of the second coil spring portion.